Re: [Minios-devel] [UNIKRAFT PATCH] lib/9pfs: Add getattr filesystem operation

[Roxana Nicolescu <nicolescu.roxana1996@xxxxxxxxx>]

Hi Costin,

Thanks for the patch.

See inline.

Roxana

On 31.10.2019 18:44, Costin Lupu wrote:
> Signed-off-by: Costin Lupu <costin.lupu@xxxxxxxxx>
> ---
>   lib/9pfs/9pfs_vnops.c | 31 ++++++++++++++++++++++++++++++-
>   1 file changed, 30 insertions(+), 1 deletion(-)
>
> diff --git a/lib/9pfs/9pfs_vnops.c b/lib/9pfs/9pfs_vnops.c
> index 53d00b8e..87fde712 100644
> --- a/lib/9pfs/9pfs_vnops.c
> +++ b/lib/9pfs/9pfs_vnops.c
> @@ -549,10 +549,39 @@ out:
>         return -rc;
>   }
>   
> +static int uk_9pfs_getattr(struct vnode *vp, struct vattr *attr)
> +{
> +       struct uk_9pdev *dev = UK_9PFS_MD(vp->v_mount)->dev;
> +       struct uk_9pfid *fid = UK_9PFS_VFID(vp);
> +       struct uk_9p_stat stat;
> +       struct uk_9preq *stat_req;
> +       int rc;
`rc` should be initialized with 0. In no error case, the return value 
will be `-rc`, which can be any trashy value on the stack.
> +
> +       stat_req = uk_9p_stat(dev, fid, &stat);
> +       if (PTRISERR(stat_req)) {
> +               rc = PTR2ERR(stat_req);
> +               goto out;
> +       }
> +
> +       /* No stat string fields are used below. */
> +       uk_9pdev_req_remove(dev, stat_req);
> +
> +       attr->va_type = uk_9pfs_vtype_from_mode(stat.mode);
> +       attr->va_mode = uk_9pfs_posix_mode_from_mode(stat.mode);
> +       attr->va_nodeid = vp->v_ino;
> +       attr->va_size = stat.length;
> +
> +       memcpy(&(attr->va_atime), &(stat.atime), sizeof(struct timespec));
> +       memcpy(&(attr->va_mtime), &(stat.mtime), sizeof(struct timespec));
I am not sure if this is the right way to do the copy.

`sizeof(struct timespec)` is longer than `sizeof(stat.atime)` and in the 
end, in the destination
we'll have some unexpected values.

> +       memset(&(attr->va_ctime), 0, sizeof(struct timespec));
> +
> +out:
> +       return -rc;
> +}
> +
>   #define uk_9pfs_seek          ((vnop_seek_t)vfscore_vop_nullop)
>   #define uk_9pfs_ioctl         ((vnop_ioctl_t)vfscore_vop_einval)
>   #define uk_9pfs_fsync         ((vnop_fsync_t)vfscore_vop_nullop)
> -#define uk_9pfs_getattr                ((vnop_getattr_t)vfscore_vop_nullop)
>   #define uk_9pfs_setattr               ((vnop_setattr_t)vfscore_vop_nullop)
>   #define uk_9pfs_truncate      ((vnop_truncate_t)vfscore_vop_nullop)
>   #define uk_9pfs_link          ((vnop_link_t)vfscore_vop_eperm)
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